Recently, a rotary drum collator has been invented that provides a much higher speed of collation. The present invention is an improvement on the collator disclosed in patent application Ser. No. 410,900 filed Oct. 29, 1973; now Pat. No. 3,970,297.
It naturally occurs that timing, phase and angle relationships between interdigitating parts of the collator are very critical. The inventive collator as described in the above application, features a rotary drum having a series of pockets for storing sheet material. The sheets are removed from the pockets to provide collations. The removal of the sheets is accomplished by rotating withdrawing arms that sweep into the rotating pockets of the drum, and frictionally remove the sheets therein disposed.
As the sheet material becomes depleted, the phase or timing angle of the rotating arms must adjust to the changing contact point for the sheets. Heretofore, a timing chain drive has provided the proper advancement of the phasing of the rotative withdrawing arms with respect to the remaining material in the drum. It has been discovered, however, that this timing chain drive only operates in the intended manner, when a standard sheet material thickness is employed. Material of a different sheet thickness is depleted from the pockets of the drum at a different rate. That is to say, that the depth or level to which the remaining material will fall within to the sprocket drive wheel, and will also assume the periodically changing angle.
While the aforementioned timing chain drive has been found to function properly, it has been discovered that it is subject to an inordinate amount of wear. It has been determined that this wear is caused by the necessity of having to spring-load the system. Spring-loading has been necessary to keep the chain taught in that span of chain which is being increased in length.
The present inventive chain drive mechanism was conceived as a means of eliminating the wear causing spring tension upon the chain drive system.